Glass Message Board
Glass Identification - Post here for all ID requests => Glass => Topic started by: NevB on October 01, 2021, 02:36:52 PM
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This is the first piece of blue uranium glass I've found. The colour is a deep turquoise but it doesn't photograph perfectly. I think it's possibly American but having trawled through the EAPGS website and the other usual places I can't find it. I assume it's a butter dish.
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It's a butter dish but neither the shade of blue (I'd expect a greenish hint) nor the glow look right to me for uranium.
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My Geiger counter tells me uranium.
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Your Geiger counter just tells you there is radioactivity. Other things are radioactive...
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certainly in that last picture, there is a lot of greenish colour showing through the blue. Originally, Annagrun and Annagelb - for example - were names given as a consequence of the green and yellow appearance of glass where uranium was added deliberately for the colour effect it produced, and the bulk of uranium glass made since then has used uranium for just that reason. In view of this reasoning then why it might be used here in what is to all intents and purposes a blue glass seems odd - perhaps this shade of blue can't be produced without including uranium, though I'm sure I've seen this blue many times without uranium - didn't Davidson make a blue of this hue?
I could be wrong, but there looks to be a slightly overall blue cast to all of these pix?
I'd agree with butter dish - all these similar things with built in underplate, and lids, are likely butters.
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As I said, the intensity of the blue is not reproduced in photos. As you speculated Paul, from another piece I've seen in this colour it was said a small amount of uranium was added to produce this intense colour. That was a piece of American glass and I don't see any reason to doubt the information. Here's another photo which I think shows the glow better. The blue colour totally disappears under UV.
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I'd never thought of it before, but assume that in coloured glass, such as this piece, manganese would never have been included ??
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I don't know but it's possible manganese was added to the initial batch of glass to produce clear glass before colourants were added later. Manganese was only added at 0.5-1.0%, adding more than that produced purple glass. IMHO the glow of this piece is too intense for manganese.
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Manganese was often added to coloured glass in my experience
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I cannot really comment on whether the piece in question is Uranium glass or not, but I noticed that the blue Sklo Union pressed glass items show a strong yellow-green glow under UV (see pic).
Michael
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I could be wrong Michael, but I think your glow stands a good chance of being from a manganese content - it doesn't look bright enough to be from uranium.
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Sorry, l wasn't clear - these post war blue pieces certainly do not contain Uranium...
Michael :)
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thanks Michael - I'd assumed, obviously wrongly, that you were suggesting your blue Sklo Union vase contained uranium - a misunderstanding all round. :) I think your vase gives support to Christine's comment that manganese was often added to coloured glass - and though I'm unsure, technically, as to why this was the case, can think only that all glass - whether clear or coloured - benefited from the addition of manganese as a de-colourant.
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It would be interesting to actually know at what percentage Manganese ceases to be a de-colourant and becomes a colourant. I suggested over 1% but don't know for sure.
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I cannot really comment on whether the piece in question is Uranium glass or not, but I noticed that the blue Sklo Union pressed glass items show a strong yellow-green glow under UV (see pic).
Michael
My blue Sklo Union ashtray does too. It gives off a very green fuzzy glow. So does some of my antique Bohemian glass. I think it's something in the make up of their glass from the area to be honest. If I'm in doubt about an old piece and it glows that colour my first thoughts are Bohemian. If it's pale orange/salmon I think Saint Louis or Russian. And if it's a yellow I generally think French old at first.
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so are you suggesting m that these orange/salmon/yellow reactions are likely to indicate a selenium content - I always had yellows down as being likely selenium. :)
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No. Not at all.
I'm just saying when I use a Uv Light on the clear glass that's what I find and the avenue it makes me explore for country of maker. I've absolutely no idea what is in the clear glass to make it have that colour.
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sure - can say that over the years whenever I've found a piece of what I think is Continental glass, the tint that the glass gives off is often of a very slight dull amber/yellow - not sufficient to suggest selenium though. When selenium is present, it gives a far stronger orange/yellow reaction.
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To be honest Paul it's such a faint reaction that it's hardly there, but if you've compared enough you see it somehow.
It just an easy guide for me to start looking. I've absolutely no thoughts on how it occurs and could never use it as an identification though.
m
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I suppose there's always the possibility that clear glass - when deprived of manganese - will give this background dull brownish/faint yellow tinge - just a thought.
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I hope we'renot talking at cross purposes :) the fuzzy tint is only there when under the blacklight. In the light of day they're all clear glass with no tint or even hint of a tint, even the older pieces.
m
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This Victorian half-pint glass is a good example of manganese fluorescence, it shows best with the light shone across the thick base, the photo actually enhances the colour.
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...and presumably the half-pint glass with manganese doesn’t register on your Geiger Counter in the way your blue butter dish does?
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Ekimp, I wouldn't have considered testing it, but actually nothing whatsoever.
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Thanks, that’s reassuring regarding your blue bowl containing uranium I would think :)
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Ekimp, the intensity of my dish's glow convinces me, I'm still trying to find a maker but if it is American they often used uranium to intensify the colour of glass and there are examples online. I've still not been able to reproduce the true blue colour in photos, it's actually a dark turquoise/teal blue.